Planetary Protection seems to involve efforts to make sure that spacecraft do not carry Earth microorganisms to other planets, contaminating them. And conversely, making sure that spacecraft returning samples to Earth from other planets aren't carrying potentially dangerous extraterrestrial life, some analogue of our microorganisms. They say that NASA is obligated to do this due to federal requirements and international treaties.

It seems to me that the people most suited to this work might be microbiologists.